Japanese Utility Model Publication No. Sho 55-47, 740 discloses a conventional brake in which a tilted washer having non-parallel sides is interposed between the cantilever and the mounting pin for the shoe inserted into the fixing bolt supported to the lever, with the fixing bolt being inserted through the washer and cantilever and being tightened by a nut. The nut is loosened to turn the washer to thereby adjust the position of the shoe with respect to the cantilever.
Since the washer is turned to tilt the fixing bolt at the nut mounting end with respect to the cantilever, the cantilever surface opposite to the nut should be made spherical and also a washer and a nut to be applied to the outer surface of the cantilever should also be spherical.
As a result, workability deteriorates and it is difficult to machine the contact surfaces of the cantilever, washer and nut to closely approximate a sphere so that these members are in close contact with each other, with the result that a problem is created in that the tightening function of the nut is decreased. In order to solve this problem, when the washer and nut are intended to have a large contact area, the spherical portions of the cantilever must be made relatively thin and thus weak in strength. Hence, the cantilever is required to be large-sized to provide the necessary thickness, with the shoe spaced relatively far apart from the base in order to increase the amount of deflection at the portion between the base and the shoe; therefore, this latter portion should be strong and large in size. This creates a problem in that the brake becomes larger in external size and weight and expensive to produce.